Rudder Normal Force Coefficient

The rudder is considered as a symmetrical aerofoil. This type of aerofoil represents the conventional rudder. Fujii and Tsuda References 28 performed extensive rudder normal force measurements in open water and suggested the following semi-empirical formula for rudder normal force coefficient:

where is the rudder normal force coefficient. is the aspect ratio.

The intersections between hull and rudder are theoretically studied by Karasuno, References 29. The effect of the hull on the forces developed by the rudder in X and Y direction can be determined experimentally, References 30 and 31. The forces developed by the rudder are given by:

where is the water density. is the rudder area. is the relative velocity to the rudder. is the rudder normal force coefficient, is the rudder angle, is the relative flow angle to the rudder, , and are the rudder hull interaction coefficients, as shown earlier.